1. Field of the Disclosure
The present disclosure relates to a metal hydrate having an excellent crystalline property, and a preparation method thereof, wherein the metal hydrate includes an alkali metal.
2. Background of the Disclosure
A metal hydrate is a compound formed of a metal ion and a hydroxy group (OH−), and a hydrate having a strong ion bond property such as sodium hydroxide is feasibly dissolved in an aqueous solution, whereas a hydrate having a strong covalent bond property such as beryllium hydroxide (Be(OH)2) is not easily dissolved in an aqueous solution. Except for beryllium hydroxide and magnesium hydroxide, most metal hydrates of the alkali group and the alkaline earth group are well dissolved in water, whereas hydrates of transition metals, post-transition metals and lanthanum metals including Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Ru, Rh, Ag, Cd, Ir, W, Au, Hg, Al, Ga, In, Sn, Tl, Pb, Bi, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu are water-insoluble. The water-soluble metal hydrates are used as strong bases, and the water-insoluble metal hydrates are utilized as fire retardants, antacids, adsorbents and the like. Besides, the water-insoluble hydrates are used as a catalyst, an fluorescent substance, an electrode material, a secondary battery material, a fiber material, a magnetic material, and so forth.
In addition, the aforementioned water-insoluble metal hydrates may be converted into metal oxides by heat treatment at a high temperature of 500° C. or more, and thus are also utilized as a precursor for preparing oxides. For example, yttrium hydrate (Y(OH)3) generally forms a structural body such as a rod, a wire, a tube and a layered structure due to the hexagonal phase, and the yttrium hydrate with this structure may be dehydrated by heat treatment at a high temperature (for example, 500° C. or more) to be converted into yttrium oxide (Y2O3). At this time, it is possible to form an yttrium oxide (Y2O3) having a structure such as a rod, a wire and a tube according to the characteristics in is which the structure is maintained (See: Shiba, F., et at., CrystEngComm, 2013, 15: 1061-1067).
Meanwhile, US Patent Application Publication No. 2011/0143139 is related to a method for preparing a metal hydroxide nanoplatelet, wherein the metal hydroxide nanoplatelet is composed of oxides or hydroxides of various metals by an electrochemical method (using an electrolyzer). The electrochemical method is disadvantageous in that the method requires complicated steps and is not economically efficient as compared to a combustion synthesis method.
U.S. Pat. No. 5,879,647 discloses a method for precipitating particles of yttrium oxide in a solution containing an yttrium salt (a method using urea). However, since complicated processes are required for controlling the particle size of yttrium oxide, and the production rate thereof is low, the method is not suitable for a large-scale production.
Further, the water-insoluble metal hydrate may be produced by a liquid-phase method such as a hydrothermal synthesis or a precipitation method from a nitrate, a chloride, a carbonate and the like of metal. However, metal hydrates produced by the above-described liquid-phase method generally tend to have low crystallinity and be unstable. In addition, it is difficult to dope the water-insoluble metal hydrate prepared by the liquid-phase method with an alkali metal component due to the characteristics of the process. These limitations in the process make it difficult to uniformly contain an alkali metal component in a metal hydrate or an oxide derived therefrom, restricting an utility of a metal oxide.
Therefore, there has been an urgent need in the art for a preparation method of solving the above-described drawbacks.
Throughout this application, various patents and publications are referenced and citations are provided in parentheses. The disclosure of these patents and publications in their entities are hereby incorporated by references into this application in order to more fully describe this invention and the state of the art to which this invention pertains.